Field of Invention
The present invention relates to a passive component structure and a manufacturing method of the passive component structure.
Description of Related Art
A conventional inductor structure may include a silicon substrate and plural copper bumps. The silicon substrate has plural bond pads. The copper bumps that can transmit high frequency signals are respectively formed on the bond pads by electroplating. In the subsequent manufacturing process, ball grid array (BGA) or conductive protrusions may be electrically connected to the bond pads of the silicon substrate through the copper bumps. Tin and lead cannot directly adhered to the copper bump. Hence, after the copper bump is electroplated completely, a nickel layer and a gold layer need to be electroplated on the copper bump in sequence. The nickel layer has a high resistance property to prevent the gold layer and the copper bump from melting with each other in a high temperature environment, and the gold layer may prevent the copper bump from oxidation.
A solder ball or a conductive protrusion may be adhered to the copper bump through the nickel layer and the gold layer. However, only few copper bumps of an inductor structure need to be electrically connected to the conductive protrusions or the solder balls in the following manufacturing process, such as a BGA process or a wire bonding process. Most of the copper bumps in fact do not need to be electrically connected to the solder balls or the conductive protrusions. In general, when the inductor structure is manufactured, all of the copper bumps are going to be electroplated with the nickel layers and the gold layers due to the limited process capability.
As a result, electroplating materials (e.g., gold) may be wasted. Further, the nickel layers and the gold layers that are electroplated on all of the copper bumps may increase the total resistance of the circuits of the inductor structure, which reduces the efficiency of the inductor structure. As such, it is difficult to improve the inductance quality factor of the inductor structure.